I got a Starrett 196 back plunger indicator in a lot of tools I just bought. When the back plunger is pushed in the hand visibly moves towards the crystal. There also seems to be some lost motion or at least the movement is not smooth. I intend to do a dissection, but what are the odds this is a sign of a fatal problem with the indicator? I looked at the exploded view on Starrett's 3d parts catalog but things like the jewel bearings (my suspects) don't show.